Jet engines

ABSTRACT

Liquid pumped at constant velocity through a pipe is injected with an excess quantity of gas under pressure which is thoroughly mixed with the liquid in the pipe to form a small bubble dispersion and the accelerated jet of liquid issuing from the outlet end of the pipe may be used to propel a boat or a land vehicle. In a jet engine operating on the above principle, a pump driven by a prime mover draws in water from the vicinity of a boat or from a tank mounted on a road vehicle and delivers it under constant pressure through a jet pipe having a perforated section at or near its outlet surrounded by a chamber to which gas under pressure is fed from the exhaust of the prime mover or from a compressor driven by the prime mover and the accelerated jet of water discharged through the pipe outlet produces a propulsive thrust or is employed to drive the wheel of a turbine.

limited States Patent Earshy Tell, 22, 1972 [54] ,liiE'li ENGilNlEfi Primary Examin er--Cla.rence R. Gordon 72 inventor: Charles ll. Ball-shy, Little Croft, Two Mile Emma" Ash, Horsham, Sussex, England 57] ABSTRAQT 22] Filed: Dec. 31, W69

{52] 111.5.CIL. ....60/221l, 115/14, 239/8 [51] lint. C1 ..1B163h 111/08 [58] Field oil Search ..60/221, 204

[56] litellerences Cited UNITED STATES PATENTS 2,528,354 10/1950 Flanagan .....60/221 3,265,027 8/1966 Brown .60/221 X 3,273,333 9/1966 Roulund .....60/221 3,342,032 9/1967 Cox ..60/221 3,365,891 1/1968 Williams ..60/221 3 500,643 3/1970 Hoeptner ..60/204 Liquid pumped at constant velocity through a pipe is injected with an excess quantity of gas under pressure which is thoroughly mixed with the liquid in the pipe to form a small bubble dispersion and the accelerated jet of liquid issuing from the outlet end of the pipe may be used to propel a boat or a land vehicle.

In a jet engine operating on the above principle, a pump driven by a prime mover draws in water from the vicinity of a boat or from a tank mounted on a road vehicle and delivers it under constant pressure through a jet pipe having a perforated section at or near its outlet surrounded by a chamber to which gas under pressure is fed from the exhaust of the prime mover or from a compressor driven by the prime mover and the accelerated jet of water discharged through the pipe outlet produces a propulsive thrust or is employed to drive the wheel of a turbine.

v PATENIEUFEB22 m2 3.643.438

SHEET 1 BF 2 INVENTOR CHARLES RUTLAND BARSBY BY NORRIS & BATEMAN PAIENIEDFEB22 I972 3,643 ,438

sum 2 OF 2 INVEN'IOR CHARLES RUTLAND BARSBY BY NORRIS & BAIEMAN JET ENGINES This invention relates to apparatus for accelerating a liquid through a jet nozzle and is based on the well-known principle of the airlift pump which essentially comprises a vertical pipe the lower end of which is immersed in the liquid to be pumped and is connected below the surface of the liquid to a source of air under pressure. The consequent aeration of liquid inside the tube lowers its mean density and the liquid column rises to balance the submergence head. Liquid then flows from the upper end of the tube at a rate dependent upon the volume of air used and the jet so obtained can be made to do useful work such as rotate a turbine wheel placed in its path. The degree of slip which occurs in such a pump, however, impairs its efficiency and renders it incapable of high-power operation.

It has now been found, according to one aspect of the invention, that if a sufficient quantity of air or gas is injected into and thoroughly mixed with liquid which is propelled through a pipe of substantially constant diameter at a constant velocity the consequent pressure in the pipe and the reduction in density of the liquid due to aeration will force the liquid out of its discharge end at a substantially higher velocity as a gas-inliquid dispersion and the energy of the jet so produced can be absorbed in a turbine wheel, used for jet propulsion or for other purposes such as firefighting.

The air or gas must be mixed as thoroughly as possible with the liquid in order that the latter may be accelerated by dispersion of the air or gas in the liquid and/or by entrainment of the liquid with the air or gas, and to obtain an adequate degree of dispersion the pipe or a gas supply tube within the pipe is preferably formed at the point of entry of the gas with a perforated section.

If fuel is added to the air or gas to form a combustible gas which is continuously ignited at the point of entry to the pipe the liquid will emerge from the pipe at an even higher velocity.

Various practical embodiments of the invention are illustrated, by way of example, in the accompanying diagrammatic drawings.

FIG. 1 is a diagrammatic side view partly broken away and in section illustrating the invention according to a first embodiment;

FIG. 2 is a diagrammatic side view like FIG. ll showing a further embodiment including a further mixing stage or stages;

FIG. 3 is a diagrammatic side view showing another embodimerit wherein the compressor is omitted;

FIG. 4 shows a flow reversing arrangement that may be used with any embodiment; and

FIG. 5 is a diagrammatic side view showing still a further embodiment adapted for land vehicles.

The inboard, outboard or inboard/outboard unit shown in FIG. I for mounting in or on a boat to achieve jet propulsion comprises a pump 1 for raising water through a suction inlet 2 and supplying it under pressure to the intake of a jet pipe 3 formed downstream of the intake with a perforated section 4 surrounded by a chamber 5, a compressor 6 for supplying air or a combustible gas under pressure to the chamber through a pipe 7 and, when a combustible gas is supplied to the chamber, a spark plug 8 mounted at the inlet to the chamber for continuously igniting the combustible gas upon entry. The pump 1 and compressor 6 are both driven by a standard power unit 9, and variable speed drives can be interposed between the power unit and the compressor and/or the pump to permit of variation of the gas/liquid ratio in order to achieve optimum operating conditions.

In operation, the whole pump l or just the suction inlet 2 is immersed in the water with the suction inlet facing the bow of the boat and volumes of air or gas greater than the volume of water passing through the jet pipe 3 up to a critical value dependent on the nature or condition of the water can be dispersed in the form of small bubbles in the water resulting in a big increase in the velocity of the water and ajet thrust applied to the boat. The velocities so obtained are much higher than with conventional pump or impeller type jets at present in use on boats. A still higher degree of gas dispersion and therefore a higher water velocity and thrust can be obtained by adding a small quantity of detergent or other surface active agent to the water flowing through the jet pipe 3 to the perforated section 4.

The unit shown in FIG. 1 may be provided, as shown in FIG. 2 with a second stage in the form of a T-piece l0 supplied with air or gas from the compressor 6 through a pipe lll connected to the pipe 7 or from the exhaust of the prime mover. This second stage produces large bubbles in the smail bubble dispersion flowing from chamber 5 which bubbles act to further accelerate the water. Air or gas from the compressor 6 may be supplied to yet a third stage 12, shown in broken lines in FIG. 2 through a pipe 13 in order to entrain the dispersion from the second stage 10 and draw it out of the jet pipe 3 at an even greater velocity.

In the modification shown in FIG. 3, the compressor 6 is omitted and the exhaust gases from the power unit 9 are supplied to the chamber 5 through a pipe 14. Gas dispersion jets of the kind described can also be employed to make conventional pump-type jets more efficient.

Steering of the boat is easily performed by altering the direction of thrust of the jet in conventional manner, e.g., by means of hinged mounting when the unit is an outboard one or by means of flexible tubing when the unit is of the inboard or inboard/outboard type.

Reversing of the boat can be carried out either by reversing the direction of flow of the jet or by diverting the water stream away from the jet pipe 3 to a separate reversing jet. The direction offlow of the jet from the jet pipe 3 may be reversed, as shown in FIG. 4, by providing a pipe bend l5 which is hinged to the pipe 3 for movement in the direction of the arrows 16 about a horizontal axis 17 between an upper inoperative position and a lower operative position in which it receives the jet from the pipe 3.

A unit constructed in accordance with the invention can possess a high power/weight ratio and also a number of other advantages over conventional marine propulsion units and also over jet propulsion units which rely on straightforward pumping of a liquid or gas. Compared with the latter much higher liquid velocities at the jet are achieved and compared with the former no efficiency is lost due to transmission of power through a mechanical linkage to a propeller or propeller slip in the water. Furthermore the unit, which does not transmit mechanical vibration to the hull and can drive a boat more efficiently at much higher speeds than a conventional unit, may be employed as an auxiliary outboard type of unit which may, if required, be operated after the boat has been got under way by means of the usual propeller drive.

For use on land the liquid can be pumped to the intake of the jet pipe 3 from a reservoir 18 (FIG. 5) and the outlet noz' zle can be made to discharge into a turbine wheel I), rotation of which can be transformed in conventional manner into useful work. In this embodiment the mixture of gas and liquid leaving the turbine wheel is collected and passed through a condenser, collector or cooler 20 before being returned to the reservoir for reuse.

The invention may also be used to increase the velocity of liquid emerging from the nozzle of a fire-extinguishing hose by supplying a pressurized gas, which may be free of oxygen or not as required, to a chamber surrounding a perforated section of the hose.

I claim:

1. A liquid jet propulsion unit comprising a prime mover, a pump operatively connected to said prime mover for operation thereby and communicating on its suction side with a source of liquid, a jet pipe connected at one end to the discharge side of said pump and formed downstream of said connection with a section of uniform diameter having a perforated wall, a closed chamber surrounding a part of said uniform diameter section and communicating with the interior of said pipe through said perforated wall and means for supplying gas under pressure to said chamber in order that it may enter said pipe through the perforated wall and thoroughly mix with the liquid pumped through the pipe to form a dispersion of small bubbles therein which causes acceleration of the liquid stream.

2. A jet propulsion unit as claimed in claim 1, wherein said means for supplying gas under pressure to said chamber is the exhaust of said prime mover.

3. A jet propulsion unit as claimed in claim 1, wherein said means for supplying gas under pressure to said chamber is a compressor driven by said prime mover.

4. A jet propulsion unit as claimed in claim 1, wherein said gas is combustible and including a spark plug mounted in said chamber adjacent the inlet thereof for igniting the gas supplied thereto.

5. A jet propulsion unit as claimed in claim 1, including a T junction of uniform diameter equal to that of said uniform diameter pipe section, the crosspiece of which is inserted between the downstream end of said uniform diameter section and the upstream end of a tail section of similar diameter, and the stern portion of which is connected to said means for supplying gas under pressure to said chamber, whereby additional gas is injected into the mixture of gas and liquid flowing into said crosspiece to form large bubbles which further accelerate said liquid stream through said tail section.

6. A jet propulsion unit as claimed in claim 5, wherein the downstream end of said tail section is surrounded by a nozzle connected to said means for supplying gas under pressure to said chamber, whereby more gas is supplied to entrain the liquid accelerated by the large bubbles and draw it through the tail section of the pipe and at an even higher velocity. 

1. A liquid jet propulsion unit comprising a prime mover, a pump operatively connected to said prime mover for operation thereby and communicating on its suction side with a source of liquid, a jet pipe connected at one end to the discharge side of said pump and formed downstream of said connection with a section of uniform diameter having a perforated wall, a closed chamber surrounding a part of said uniform diameter section and communicating with the interior of said pipe through said perforated wall and means for supplying gas under pressure to said chamber in order that it may enter said pipe through the perforated wall and thoroughly mix with the liquid pumped through the pipe to form a dispersion of small bubbles therein which causes acceleration of the liquid stream.
 2. A jet propulsion unit as claimed in claim 1, wherein said means for supplying gas under pressure to said chamber is the exhaust of said prime mover.
 3. A jet propulsion unit as claimed in claim 1, wherein said means for supplying gas under pressure to said chamber is a compressor driven by said prime mover.
 4. A jet propulsion unit as claimed in claim 1, wherein said gas is combustible and including a spark plug mounted in said chamber adjacent the inlet thereof for igniting the gas supplied thereto.
 5. A jet propulsion unit as claimed in claim 1, including a T-junction of uniform diameter equal to that of said uniform diameter pipe section, the crosspiece of which is inserted between the downstream end of said uniform diameter section and the upstream end of a tail section of similar diameter, and the stem portion of which is connected to said means for supplying gas under pressure to said chamber, whereby additional gas is injected into the mixture of gas and liquid flowing into said crosspiece to form large bubbles which further accelerate said liquid stream through said tail section.
 6. A jet propulsion unit as claimed in claim 5, wherein the downstream end of said tail section is surrounded by a nozzle connected to said means for supplying gas under pressure to said chamber, whereby more gas is supplied to entrain the liquid accelerated by the large bubbles and draw it through the tail section of the pipe and at an even higher velocity. 